Contractors Turn Strategy Into Reality

A Garland, Texas, interceptor project
took five years to get to the street. Now
the contractors are making capacity
improvements a reality by installing
48-inch outside diameter (OD) pipe
over about 18 months.

“Not a lot of people can do a big
line,” said Larry Lisowski, an engineer
who works for Gajeske Inc. of Houston.
Business has been good because
Gajeske can install large diameter pipe.
Bob Gajeske Jr., vice president of the
company, estimates 2007 revenues at
$27 million.

The city of Garland awarded a
$41.6 million contract to the Oscar
Renda Contracting Co. of Roanoke,
Texas. Renda awarded a $3.2 million
subcontract to Gajeske, which employs
about 50 people.

This bid project involves installation
of a raw wastewater force main
and sludge transfer force main linking
the 24-million-gallons-per-day
(mgd) Rowlett Wastewater Treatment
Plant to the recently expanded 30-
mgd Duck Creek Wastewater Treatment
Plant. Gajeske’s part of the project
was to provide nearly four miles
of 48-inch OD high-density polyethylene
pipe (HDPE), fuse those
sections together, and also weld
another 11 miles of 8-inch OD
HDPE sludge force main sections
that will transport solids from Duck
Creek back to Rowlett.

“We are very excited about this
project, which has some challenging
sections and provides us with the
opportunity to utilize our experience
and expertise in large-diameter HDPE
pipe,” said Gajeske.

Lisowski said that more cities have
been specifying bigger diameter pipe
so that the water and sewer lines could
accommodate greater flows as cities
continue to increase in population.

On the job
In a Garland park along Lake Ray
Hubbard, miles of 48-inch HDPE
pipe stretched out as far as the eye
could see. The pipe was trucked in
from Performance Pipe manufacturing
facilities in Brownwood, Texas,
and Wellford, S.C. The pipe company
is a division of Chevron Phillips
Chemicals Co. Many pipe sections already had been fused together on Oct. 4,
ready to be put into a trench and transport
excess flow from the Rowlett plant to the Duck
Creek facility.

Rob Jaynes worked with other Gajeske crew
members at the site, fusing large sections of pipe
together using a 1648 MegaMc fusion machine
from McElroy Manufacturing Co. The machine
holds two pipe sections in large clamps, sheers
the butt ends clean and level, and then applies
500 degrees Fahrenheit of heat for about two
minutes. Jaynes flips a second switch, and the
machine also applies 1,000 pounds of joining
pressure to the sections. According to Gajeske,
the joined pipe must cool completely, about 30
minutes, before the process is complete. Each
section takes Jaynes one hour. Then a crew
member starts up the Volvo crawler to pull the
newly fused sections down the grassy length of
city park and the cycle begins again.

The right pipe for the job?
This is where the HDPE meets the load. The Plastic
Pipe Institute has said that HDPE has been
used in sewers for
more than 25 years
without showing significant
changes in
physical or chemical
properties. But not
everyone is on board
with that idea.

“It is true that
HDPE pipe historically
is not used
extensively in wastewater applications,” said
David Timmerman, P.E., Black & Veatch’s project
manager who is working with the city.
“The reason it was closely evaluated,” Timmerman
explained, “is because we have a
pumped transfer line from the Rowlett plant
into the junction manhole, so we needed a pipe
that was capable of pressure flow. The city also
wanted a line that was relatively free of joints—
fusion welded is an attractive feature. Another
nuance is that the pipeline does not flow
continuously uphill; the last quarter of the segment
flows downhill, so the pipe will be partially
full, which gives an opportunity for
corrosion. HDPE won’t corrode.”

Timmerman said that the Texas Commission
on Environmental Quality, Wastewater Permitting
Section, does not typically approve
HDPE for this kind of application. The agency
requires force mains to have a minimum pipe
working pressure of 150 pounds per square inch.
The Black & Veatch team submitted documentation
showing that, given this project’s
hydraulic design conditions, HDPE pipe could
safely convey the flow with a lower pipe design
working pressure. The section approved a variance,
allowing the HDPE pipe to be used.

The large-diameter HDPE pipe that Gajeske
worked on will serve as the pump transfer line
from Rowlett and ties to a manhole that ties to
a new, 60-inch interceptor sewer, made from
fiberglass, which will replace a smaller diameter
pipe and expand city capacity. The 60-inch line
was provided by HOBAS Pipe of Houston. The
8-inch, HDPE sludge force main sections were
supplied by JM Eagle of Livingston, N.J. The
smaller diameter pipe runs parallel to existing
pipe and will allow the city to easily perform
maintenance.

Work flow
As the primary contractor, Renda’s General
Superintendent Chris Williams will oversee the
work of Gajeske and construct and install the
additional lines to provide more conveyance
capacity through a portion of the drainage
area and to the plants.

Jaynes said he has worked with a lot of contractors.
He said he received instruction from
Williams and then was left to do the job. “I like
that the prime contractor didn’t feel the need to
micromanage the process,” Jaynes said, adding
that the teamwork of the groups on the project
has made the job “more fluid.”

Garland’s interceptor project has taken so
long to “get to the street” because almost all
of the land used in the project is within a
floodplain. “There was significant environmental
work that had to be done,” Timmerman
said.

And apparently there still is more construction
work to be had. Timmerman said the city
is about to put another contract out on the street
for the Rowlett Transfer Pump Station. “We calculated
flows to the plant and they exceeded
capacity, so we are transferring flow from
Rowlett to the collection system to the plant,”
he explained. That contract will be about $6.5
million, he added.

This article originally appeared in the 12/01/2007 issue of Environmental Protection.